Module1-Intro to Lasers Flashcards
- When was the first working laser devise used? 2. what type of crystal was used? 3. What color was it?
- 1960 2.Ruby Crystal 3. Red beam
What is LASER an acronym for?
Light Amplification by Stimulated Emission of Radiation
What are the three terms used when comparing normal light with laser light?
1.wavelength/color (multi/monochrome) 2.collimation 3.coherent
Units of Measurement: wavelength
NM
Units of Measurement: pulse duration (3)
US, PICO, NANO
Units of Measurement: pulse repetition
Hz
Units of Measurement: ENERGY (2)
J or MJ
Units of Measurement: POWER (2)
Average (W), Peak (W)
Units of Measurement: Irradiated Area (2)
cm^2 or mm^2
Units of Measurement: Energy density
J/cm^2
Units of Measurement: Fluence
J/cm^2
Units of Measurement: POWER density
W/cm^2
Which type of emission is being described?: ENERGY ABSORPTION OF ELECTIONS (VIA ABSORBING A PHOTON), RESULTS IN AN ELECTRON REACHING AN EXCITED LEVEL, THEN THE ELECTRON FALLS BACK TO ORIGINAL STATE WITH THE EMISSION OF A PHOTON
Spontaneous Emission
Which type of Emission is being described?: SECOND PHOTON INTRODUCED BEFORE SPONTANEOUS FALL BACK OCCURS, RESULTS IN STIMULATED FALLBACK TO ORIGINAL LEVEL WITH THE STIMULATED RELEASE OF 2 PHOTONS
Stimulated Emission
What are the two properties of a photon in stimulated emission that make it the definition of a laser?
the photons are IDENTICAL and COHERENT
What principle is this describing? A THEORY THAT BUILDS OFF OF A SINGLE EPISODE OF STIMULATED
EMISSION, IF EACH OF THE TWO IDENTICAL PHOTONS LEAVING THE ATOM STIMULATE OTHER ATOMS TO EMIT AND SO ON….
Avalanche Principle
What is the term for this?: MORE ATOMS IN THEIR EXCITED STATE THAN IN THEIR GROUND STATE, THUS CREATED MORE OPPORTUNITIES FOR STIMULATED EMISSION TO OCCUR
Population Inversion
Whats the difference between ionizing radiation and non-ionizing radiation?
Ionizing-electron breaks away from the atom. Non-ionizing-electron is just excited and stays with electron
What parts of the ElectroMagnetic Spectrum do lasers operate?
Visible and InfraRed
What two parts of the ElectroMagnetic Spectrum do lasers use to work on Soft Tissue?
Nd:YAG and Diodes = NEAR InfraRed….CO2 = Far InfraRed
What part of the ElectroMagnetic Spectrum does a laser use to work on Hard Tissue?
MID InfraRed
What are the 3 main components to a Laser?
1.Active Medium 2. Pumping Mechanism 3.Optical Resonator
Which component of a laser gives the laser its generic name? What are some examples?
The Active Medium…Erbium:YAG, Diode-semiconductor, CO2
What are the two types of pumping mechanisms?
- rapidly flashing lamp (free running lasers) 2.electrical current field (continuous wave lasers)
What are the two Modes of Operation for a laser?
1.Continuous Wave 2.Pulsed
Which Mode of Operation am I describing? The laser is activated and emission is constant.
Continuous Wave
Which Mode of Operation am I describing? The laser energy is produced in very short pulses by a flash-lamp.
Free-Running Pulsed
What are the 4 ways a laser can interact with tissue? Which is the ONLY interaction that is useful in dentistry?
RATS! 1.Reflection 2.Absorption 3.Transmission 4.Scatter…..ABSORPTION is the only interaction that can do work
What are the three types of absorption that a laser has on tissue?
1.Thermal 2. Chemical 3.Acoustic
What are the 4 CHROMOPHORES in the tissue that absorb laser light?
1.water 2.hemoglobin 3.melanin 4.carbonated hydroxyapatite
What are the 2 main chromophores at work in HARD tissue?
Water and Carbonated Hydroxyapatite
What are the 2 main chromophores at work in the soft tissue EPITHELIUM?
Water and Melanin
What are the 3 chromophores at work in the soft tissue SUB-Epithelium?
1.Water 2.hemoglobin 3.OXY-hemoglobin
Temperature effects on tissue- what happens at >37 deg C?
Hyperthermia
Temperature effects on tissue- What happens at >50 deg C?
BACTERIA Inactivated
Temperature effects on tissue- What happens at >60-90 deg C?
Coagulation and Irreversible PROTEIN DENATURATION
Temperature effects on tissue- What happens at >100-150 deg C?
Vaporization
Temperature effects on tissue- What happens at >200 deg C?
Carbonization
Temperature effects on tissue- At 50 C, non-________ bacteria, including ________, are readily deactivated
non-SPORULATING…ANAEROBES
To achieve hemostasis, a tissue temperature of ____ C must be obtained.
60 degrees C
For removal (excision) of healthy tissue, a temperature of at least ____ C must be reached
100 C
Did you know…soft tissue COAGULATIOn by ____ lasers is 10x more efficient than Erbium lasers
CO2
Did you know….soft tissue ABLATION by CO2 lasers is 1,000x more efficient than _____ lasers
diode
Did you know…InfraRed CO2 lasers at 10% absorption has 4x less _____ than Near InfraRed and 3x less ______ than Erbium
HEATING…HEATING
Did you know..coagulation depth is PROPORTIONAL to ________ depth
absorption
What is the RANGE for possible diameters of blood vessels in the SUB-Epithelium? What is the AVG?
21-40 micrometers…31 micrometers
Which laser is most likely to cause wide spread tissue damage during coagulation?
Near-IR DIODE
Which laser is highly accurate and efficient, but has poor coagulation efficiency?
Mid-IR Erbium lasers
Which laser is highly efficient and accurate and has excellent coagulation?
CO2 laser
A PROPERTY OF EM WAVES IN WHICH EACH WAVE IS OF THE SAME WAVELENGTH AND PRECISELY IN PHASE WITH EACH OTHER
Coherent
A PROPERTY OF EM WAVES WHERE ALL THE WAVES ARE PARALLEL
Collimated
Peak Power = what / what?
peak power = pulse energy (J) / pulse duration (s)
Average Power = what / what?
avg power = pulse energy (J) / Pulse rate (Hz)
Decreasing the diameter of a tip by 2x decreases the area working on by a factor of __x, therefore its a __x increase in the ______
4x…4x increase in the FLUENCE
Safety-what is the definition of MPE?
Maximum Permissible Exposure-level of exposure without injury
Safety-does focal magnification have an effect on eye injury from a laser?
YES…a 10^5 GAIN on the retina (1mW/cm^2 into eye = 100 W/cm^2 on the Retina!!!!!)
What thickness of mask should be used for the plumes made?
0.1 micron thick
